WASHINGTON - Lawmakers from both sides are questioning President Barack Obama's motives in authorizing U.S. air strikes in Libya and whether he had the authority to do so.

One year before taking office, then-candidate Obama was asked about the president's authority to bomb Iran without authorization from Congress.

"The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation," Obama told the Boston Globe in 2007.

"As commander in chief, the president does have a duty to protect and defend the United States," he said. "In instances of self-defense, the president would be within his constitutional authority to act before advising Congress or seeking its consent."

Yet, when the United States joined the fight against Libyan dictator Moammar Gadhafi on Friday, no request from Congress was made.

For more on the debate surrounding the United States' stake in Libya, CBN News spoke with national security expert Scott Wheeler. Click play for his comments following Jennifer Wishon's report.

In a letter sent to Congress Monday, Obama told Congress he authorized the action, "To prevent a humanitarian catastrophe and address the threat posed to international peace and security by the crisis in Libya."

"The United States does not have a King's army," Rep. Roscoe Bartlett, R-Md. said in response. "President Obama's unilateral choice to use U.S. military force in Libya is an affront to our Constitution."

Rep. Dennis Kucinich, D-Ohio, has vowed to offer an amendment to the next budget bill that would prohibit taxpayer dollars from being used to fund U.S. military operations in Libya.

Some Democrats are also questioning President Obama's motivation for using military action in Libya. They believe the decision had more to do with Libya's rich oil reserves than America's concerns about violence being carried out by the Gadhafi regime.

Democrats and Republicans are frustrated with the president's inability to explain why the U.S. has an interest in Libya, but not in other nations where citizens are also fighting oppressive regimes.

Meanwhile, President Obama was briefed by his national security team on the situation in Libya, Tuesday.

Gen. Carter Ham, chief of U.S. Military Command in Libya, said the number of U.S. missions in the country are already decreasing.

The administration's goal is to step back and let NATO allies take the lead. The president expects this to take days, not weeks.

Ultimately, Obama stressed the final outcome is up to the Libyan people.

"Democracy can't be imposed from the outside," Obama said. "It must spring from within, from the hearts and souls of those who seek it."

Jennifer Wishon

CBN News White House Correspondent

Jennifer Wishon is the White House correspondent for CBN News based in the network’s Washington, D.C. Bureau. Before taking over the White House beat, Jennifer covered Capitol Hill and other national news, from the economy to the 2010 oil spill in the Gulf of Mexico. Follow Jennifer on Twitter @JenniferWishon and "like" her at Facebook.com/JennWishon.